The present invention relates to a vertically-arranged rubbing finisher having symmetrically--located output bobbins with single slubbings.
Rubbing finishers are already known in which the slubbings which pass through the drawing and rubbing units travel paths located in a common longitudinal vertical plane and which output bobbins with single slubbings.
In such known rubbing finishers, each rubbing unit is traversed by a pair of slubbings each of which is wound, with the aid of a twisting and guide device, on a spool carried by one of the two underlying groups of bobbin winding devices.
Each group of winding devices is constituted by a plurality of mutually-aligned, driven drive rollers, the common horizontal axis whereof is parallel to the length of the machine, and towards which the various spools on which the bobbins are to be formed are constantly thrust.
Each of these spools is supported at its end by a pair of arms mounted for rotation about axes parallel to the drive rollers and pivotable, possibly against the action of resilient means, so as to move the spool away from its drive roller.
Each group of winding devices is also disposed and arranged so that it can deposit the bobbin just formed on a movable cradle or tray arranged to transfer this bobbin to the outlet of the machine and so that it can receive a new, still-empty spool before the respective arms return to the starting position in which this spool contacts its drive roller, thus enabling the formation of a new single-slubbing bobbin.
In known practical embodiments of machines with the characteristics mentioned above--which will, for simplicity, be termed "rubbing finishers of the specified type" below--the two groups of winding devices are staggered relative to each other in height and are arranged so that, from the rubbing units, the slubbings reach one of them by moving in the vertical plane of symmetry of the groups while they reach the other after travelling a path which is inclined to this plane.
Moreover the groups of winding devices are arranged so that they can discharge their bobbins which have just been formed in two phases into the same trays or cradles and can take up new, still-empty spools from the same loaders.
Compared with conventional systems in which double-slubbing bobbins are formed, the machines in question have the indisputably great advantage of being able to exchange bobbins in the finisher, and also in the subsequent spinning stage, twice less frequently than is necessary when double-slubbing bobbins are output, with a consequent considerable increase in the productivity of the systems.
The known structure is not, however, without drawbacks. The fact that the groups of winding devices are staggered in height considerably increases the bulk of the machine in this direction.
At the end of their formation by the two separate groups of winding devices, the bobbins must, per force, be discharged in two successive phases, a first for discharging the bobbins formed by the upper groups of winding devices and then one for those formed by the lower winding devices. This doubles the time needed to carry out this stage in the automatic bobbin-exchange cycle.
Furthermore, because of the need to allow the bobbin-carrying arms and the bobbins themselves to effect the necessary rotational movements for the discharge, in the presence of each other, it is necessary to make the spools somewhat shorter than those usable in a double-slubbing bobbin finisher, for the same length of machine and number of bobbins.
The increased height of the machine makes access less easy, not only to some of the groups of winding devices but also to other parts such as the racks, rolls and rubbers.
Another serious disadvantage lies in the tension in the portions of the slubbings between the outlets from the rubbing groups and the winding devices, which have different lengths and inclinations to the median plane of symmetry of the rubbing groups. The result of this is, indeed, a difference in tension in the slubbings directed to the different winding devices giving an undesirable and often unforseeable variation in the quantity of slubbing wound on the bobbins formed by the different groups of winding devices and of the thread obtained from use of these slubbings in the subsequent spinning stage.